Recording disc and apparatus and method for reproducing recorded information

ABSTRACT

A recording disc and recorded information reproducing apparatus and method for immediately starting reproduction of information when a push-pull based tracking control is employed to reproduce recorded information from the recording disc. The recording disc comprises an information data area for recording recording marks which carry information data in columns, and a control data area for recording identification information indicative of a recording pattern of the recording marks in the information data area.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a recording disc, and a recordedinformation reproducing apparatus and method for reproducing recordedinformation from the recording disc.

[0003] 2. Description of Related Art

[0004] Today, DVD-ROM is widely used as a read-only optical recordingmedium which has previously recorded thereon information data such asaudio, video, computer data and the like. The DVD-ROM has, for example,a two-layer recording surface comprised of a first recording layer and asecond recording layer. When viewing the first recording layer from thetop layer from which a reading beam light is irradiated onto theDVD-ROM, a recording pit train carrying information data is formed on aspiral or concentric track. On the other hand, when viewing the secondrecording layer from the bottom surface of-the DVD-ROM, a recording pittrain carrying information data is formed on a spiral or concentrictrack. Specifically, when viewing the first and second recording layersfrom the top surface of the DVD-ROM, convex recording pits are formed inthe first recording layer, while concave recording pits are formed inthe second recording layer. For this reason, the recording pits recordedin the first recording layer are hereinafter referred to as the “convexrecording pits,” while the recording pits recorded in the secondrecording layer to the “concave recording pits.”

[0005] A conventional reproducing apparatus for reproducing recordedinformation from the DVD-ROM conducts a tracking servo in accordancewith a DPD (Differential Phase Detection) scheme. In the DPD-basedtracking control, reflection from the recording disc irradiated with abeam light is individually received by four photodetectors 20 a-20 d,arranged in a manner as illustrated in FIG. 1, which opto-electricallytransduce the reflection into read signals Ra-Rd which are used in thetracking control. Then, these read signals Ra-Rd are used in thefollowing calculations to generate a high frequency signal and adiagonal differential signal. The difference in phase between the twosignals is used as an error signal for conducting the tracking control:

[0006] High Frequency Signal=Ra+Rb+Rc+Rd

[0007] Diagonal Differential Signal=(Ra+Rc)−(Rb+Rd)

[0008] The employment of the DPD scheme results in the satisfactorytracking control both for the first recording layer in which convexrecording pits are recorded and for the second recording layer in whichconcave recording pits are recorded.

[0009] On the other hand, a writable recording disk such as DVD-R orDVD-RW is previously formed with a recording track which has a wobblepattern corresponding to disc addresses indicative of positions on thedisc. A recorded information reproducing apparatus for recording andreproducing information data to and from the DVD-R or DVD-RW reads thewobble pattern on the recording track formed on the recording disc torecognize the position on the disc, while information data is beingrecorded. In this event, a push-pull signal is used for reading thewobble pattern on the recording track. The push-pull signal is generatedin accordance with the following calculation using read signals Ra-Rdwhich are generated by four photodetectors 20 a-20 d as illustrated inFIG. 1 which individually receive and opto-electrically transducereflected light from the disc:

[0010] Push-Pull Signal=(Ra+Rb)−(Rc+Rd)

[0011] In addition, the recorded information reproducing apparatusconducts a tracking servo based on the push-pull signal. Specifically,the recorded information reproducing apparatus for recording andreproducing information data to and from a recording disc such as DVD-Ror DVD-RW acquires disc addresses corresponding to the wobble pattern onthe recording track based on the push-pull signal while conducting thetracking control.

[0012] Thus, the conventional recorded information reproducing apparatuswhich supports any of DVD-R, DVD-RW and DVD-ROM comprises dedicatedprocessing circuits for generating the push-pull signal, high frequencysignal and diagonal differential signal, respectively, resulting in anextremely large scale of the apparatus. There has been therefore a needfor a recorded information reproducing apparatus which only requires thepush-pull signal to conduct the tracking servo for any of DVD-R, DVD-RWand DVD-ROM.

[0013] However, the push-pull signal generated when the convex recordingpit train is read from the first recording layer of the DVD-ROM asmentioned above is opposite in polarity to the push-pull signalgenerated when the concave recording pit train is read from the secondrecording layer. As such, for reproducing recorded information from theDVD-ROM, information data is first read from a recording layer intendedfor reproduction on a trial basis. In this event, when an appropriatetracking control is failed, the polarity of the push-pull signal isreversed, followed by a repetition of the read operation again from theinitial position.

[0014] Therefore, the read operation may not be immediately started insome cases when the tracking control is conducted using the push-pullsignal for a multi-layer recording layer which has a recording layerhaving a convex recording pit train recorded therein and a recordinglayer having a concave recording pit train recorded therein, or for asingle-layer recording disc on which no recording pits are defined in aconvex or concave shape.

OBJECT AND SUMMARY OF THE INVENTION

[0015] The present invention has been made to solve the foregoingproblem, and it is an object of the invention to provide a recordingdisc, and an apparatus and method for reproducing recorded informationwhich can permit a reproducing operation to be immediately started forreproducing information data from the recording disc using a push-pullbased tracking control.

[0016] A recording disc for recording information data thereon,according to a first aspect of the present invention, includes aninformation data area for recording recording marks carrying theinformation data in columns, and a control data area for recordingidentification information indicative of a recording pattern of therecording marks in the information data area.

[0017] A recorded information reproducing apparatus according to anotheraspect of the present invention is configured to reproduce recordedinformation from a recording disc having an information data area forrecording recording marks carrying the information data in columns, anda control data area for recording identification information indicativeof a recording pattern of the recording marks in the information dataarea. The recorded information reproducing apparatus includes a readingcomponent for receiving reflected light from the recording discirradiated with reading beam light and opto-electrically transducing thereflected light into read signals by at least two photodetectorsarranged in a direction perpendicular to a track, push-pull read signalgenerator for calculating a difference between the read signalsgenerated by the respective photodetectors to output the difference as apush-pull read signal, a tracking servo for biasing the optical axis ofthe reading light beam in the direction perpendicular to the track basedon the push-pull read signal, an identification information readingcomponent for reading the identification information from the controldata area, an identifying component for identifying a recording patternof the recording marks recorded in the information data area based onthe identification information, and a polarity reversing component forreversing the polarity of the push-pull read signal in accordance withthe result of the identification made by the identifying component.

[0018] A recorded information reproducing method according to a furtheraspect of the present invention is provided for reproducing recordedinformation from a recording disc having an information data area forrecording recording marks carrying the information data in columns, anda control data area for recording identification information indicativeof a recording pattern of the recording marks in the information dataarea. The recorded information reproducing method includes a readingstep for receiving reflected light from the recording disc irradiatedwith reading beam light and opto-electrically transducing the reflectedlight into read signals by at least two photodetectors arranged in adirection perpendicular to a track, a push-pull read signal generatingstep for calculating a difference between the read signals generated bythe respective photodetectors to output the difference as a push-pullread signal, a tracking control step for biasing the optical axis of thereading light beam in the direction perpendicular to the track based onthe push-pull read signal, an identification information reading stepfor reading the identification information from the control data area,an identifying step for identifying a recording pattern of the recordingmarks recorded in the information data area based on the identificationinformation, and a polarity reversing step for reversing the polarity ofthe push-pull read signal in accordance with the result of theidentification made by the identifying step.

[0019] A recording disc according to a further aspect of the presentinvention includes a plurality of recording layers, wherein eachrecording layer has an information data area for recording recordingpits carrying information data in columns, and a control data area forrecording a convex/concave identification information indicating withrespect to at least one of the recording layers whether each recordingpit recorded on each recording layer is convex or concave.

[0020] A recorded information reproducing apparatus according to afurther aspect of the present invention is configured to reproducerecorded information from a recording disc having a plurality ofrecording layers, wherein each recording layer includes an informationdata area for recording recording pits carrying information data incolumns, and a control data area for recording a convex/concaveidentification information indicating with respect to at least one ofthe recording layers whether each recording pit recorded on eachrecording layer is convex or concave. The recorded informationreproducing apparatus includes a reading component for receivingreflected light from the recording disc irradiated with reading beamlight and opto-electrically transducing the reflected light into readsignals by at least two photodetectors arranged in a directionperpendicular to a track, a push-pull read signal generator forcalculating a difference between the read signals generated by therespective photodetectors to output the difference as a push-pull readsignal, a tracking servo for biasing the optical axis of the readinglight beam in the direction perpendicular to the track based on thepush-pull read signal, a convex/concave identification informationreading component for reading the convex/concave identificationinformation from the control data area, a convex/concave identifyingcomponent for identifying the shape of the recording pits recorded inone of the recording layers from which information is to be reproduced,based on the convex/concave identification information, and a polarityreversing component for reversing the polarity of the push-pull readsignal in accordance with the result of the identification made by theconvex/concave identifying component.

[0021] A recorded information reproducing method according to a furtheraspect of the present invention is provided for reproducing recordedinformation from a recording disc having a plurality of recordinglayers, wherein each recording layer includes an information data areafor recording recording pits carrying information data in columns, and acontrol data area for recording a convex/concave identificationinformation indicating with respect to at least one of the recordinglayers whether each recording pit recorded on each recording layer isconvex or concave. The recorded information reproducing method includesa push-pull read signal generating step for generating a push-pull readsignal based on read signals read from the recording disc, a trackingcontrol step for biasing the optical axis of the reading light beam in adirection perpendicular to a track based on the push-pull read signal, aconvex/concave identification information reading step for reading theconvex/concave identification information from the recording disc, aconvex/concave identifying step for identifying the shape of therecording pits recorded in one of the recording layers from whichinformation is to be reproduced, based on the convex/concaveidentification information, and a polarity reversing step for reversingthe polarity of the push-pull read signal in accordance with the resultof the identification made by the convex/concave identifying step.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is a diagram illustrating an exemplary arrangement ofphotodetectors 20 a-20 d mounted in a pickup;

[0023]FIGS. 2A and 2B are diagrams generally illustrating the structureof a recording disc according to the present invention;

[0024]FIG. 3 is a diagram illustrating a portion of a pattern on thesurface of a recording layer of the recording disc according to thepresent invention;

[0025]FIGS. 4A and 4B are diagrams illustrating concave recording pitsand convex recording pits, respectively;

[0026]FIG. 5 is a diagram generally illustrating the configuration of amaster recording apparatus according to the present invention;

[0027]FIG. 6 is a diagram showing a format for one track in a PEP area4;

[0028]FIGS. 7A and 7B are diagrams showing the waveforms of phaseencoded signals corresponding to one bit length of data;

[0029]FIG. 8 is a diagram illustrating the configuration of areproducing apparatus according to the present invention;

[0030]FIG. 9 is a diagram illustrating a subroutine executed by acontroller 100 of the reproducing apparatus illustrated in FIG. 8 foracquiring convex/concave identification information;

[0031]FIG. 10 is a diagram illustrating a subroutine executed by thecontroller 100 of the reproducing apparatus illustrated in FIG. 8 forsetting the polarity of a push-pull read signal;

[0032]FIG. 11 is a plan view generally showing how areas are defined ona writable recording disc commercially available for general purposes;

[0033]FIG. 12 is a diagram illustrating a portion of a pattern on thesurface of the recording disc illustrated in FIG. 11;

[0034]FIGS. 13A and 13B are diagrams showing exemplary patterns wheninformation data is recorded on a land track LT and when informationdata is recorded on a groove track, respectively;

[0035]FIG. 14 is a plan view generally showing how areas are defined ona writable recording disc for authoring; and

[0036]FIG. 15 is a diagram illustrating a portion of a pattern on thesurface of the recording disc illustrated in FIG. 14.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037]FIGS. 2A and 2B generally illustrate an exemplary structure of arecording disc according to the present invention.

[0038]FIG. 2A is a cross-sectional view of the recording disc.

[0039] As illustrated in FIG. 2A, the recording disc comprises a firstrecording layer RY1 in which convex recording pits are recorded and asecond recording layer RY2 in which concave recording pits are recorded.Each of these first recording layer RY1 and second recording layer RY2is divided into an information data area 1, a lead-in area 2, a lead-outarea 3, and a PEP (phase encoded part) area 4, as illustrated in FIG.2B. The PEP area 4 may be provided only in one of the recording layerRY1 and second recording layer RY2.

[0040] The information data area 1 is an area in which a variety ofinformation data is recorded, such as video, audio, and computer data.The lead-in area 2 in turn is an area in which lead-in data is recorded,including a recorded position, required time for reproduction, discidentification information and the like for each of information datapieces recorded in the information data area 1. The PEP area 4 in turnis an area in which phase encoded reproduction control data (laterdescribed) is recorded, including tracking information, convex/concaveidentification information and the like. The tracking information refersto such information for specifying a tracking method which should beconducted for reading recorded information from the first recordinglayer RY1 and second recording layer RY2. The convex/concaveidentification information refers to such information indicative ofwhether each of recording pits recorded in the first recording layer RY1and second recording layer RY2 is convex or concave.

[0041]FIG. 3 is a diagram, viewed from the top surface of the disc,illustrating an exemplary recording pattern in each area of the firstrecording layer RY1 (or the second recording layer RY2).

[0042] As illustrated in FIG. 3, the information data area 1 is formedwith pit trains comprised of recording pits Pt1 which carry informationdata. The lead-in area 2 in turn is formed with pit trains comprised ofrecording pits Pt1 which carry the lead-in data. It should be noted thatin the lead-in area 2, an area WE for recording the disc identificationinformation is formed with a pit train, as illustrated in FIG. 3, whichwobbles in a pattern corresponding to the disc identificationinformation. The PEP area 4 is formed with pit trains comprised ofrecording pits Pt2 corresponding to a phase encoded signal which isgenerated by phase encoded reproduction control data including theconvex/concave identification information. In this event, each of therecording pits Pt1 formed in the PEP area 4 has the same recording pitlength. In the PEP area 4, each of the recording pits pt2 is formed onone of a plurality of tracks adjacent to each other such that it is inalignment to the direction perpendicular to the track.

[0043] Here, in the first recording layer RY1, each of the recordingpits Pt1 and recording pits Pt2 is a convex recording pit whichprotrudes from the disc surface as illustrated in FIG. 4A. On the otherhand, in the recording layer RY2, each of the recording pits Pt1 andrecording pits Pt2 is a convex recording pit which recesses into thedisc surface, as illustrated in FIG. 4B.

[0044] Since the convex and concave recording pits are recorded in thefirst recording layer RY1 and second recording layer RY2, respectively,as described above, the convex/concave identification information forms2-bit data [01] indicative of that state in the foregoing embodiment.When the concave and convex recording pits are recorded in the firstrecording layer RY1 and second recording layer RY2, respectively, theconvex/concave identification information forms 2-bit data [10].Further, the convex/concave identification information forms 2-bit data[00] when convex recording pits are recorded in both the first recordinglayer RY1 and second recording layer RY2, and forms 2-bit data [11] whenconcave recording pits are recorded in both the first recording layerRY1 and second recording layer RY2.

[0045]FIG. 5 is a diagram illustrating an exemplary configuration of amaster recording apparatus for manufacturing a recording disc which hasthe structure as described above.

[0046] A master 15 is formed with a resist layer on the surface forcreating a resist pattern corresponding to the first recording layer RY1(second recording layer RY2). A spindle motor 17 rotates the master 15at a constant angular velocity. A feed stage 18 moves the master 15 andspindle motor 17 in the radial direction of the master 15. An electronicbeam irradiating apparatus 10 irradiates the surface of the resist layeron the master 15 with an electron beam in accordance with theinformation data, reproduction control data and lead-in data which havebeen input for recording on the recording disc.

[0047] A controller 25 controls the electron beam irradiating apparatus10, spindle motor 17 and feed stage 18 to create a resist patterncorresponding to the first recording layer RY1 and a resist patterncorresponding to the second recording layer RY2, respectively.

[0048] First, the controller 25 controls the electron beam irradiatingapparatus 10 to irradiate an electron beam to an area on the surface ofthe resist layer corresponding to the information data area 1 asillustrated in FIG. 3 in accordance with information data. As a result,the surface of the resist layer is formed with a latent imagecorresponding to information pits Pt1 carrying information data in thearea corresponding to the information data area 1. The controller 25also controls the electron beam irradiating apparatus 10 to irradiate anelectron beam to an area on the surface of the resist layercorresponding to the lead-in area 2 in accordance with the lead-in data.As a result, the surface of the resist layer is formed with a latentimage corresponding to recording pits Pt1 carrying the lead-in data inthe area corresponding to the lead-in area 2. The controller 25 furthercontrols the electron beam irradiating apparatus 10 to irradiate anelectron beam to an area on the surface of the resist layercorresponding to the PEP area 4 in accordance with a phase encodedsignal which is generated by phase encoding the reproduction controldata. As a result, the surface of the resist layer is formed with alatent image corresponding to recording pits Pt2 carrying thereproduction control data in the area corresponding to the PEP area 4.

[0049] The phase encoding for the reproduction control data isperformed, for example, in the following manner.

[0050] First, in the PEP area 5, a recording track corresponding to thelength of one rotation of the master 15 is regarded as one track. Inthis event, one track is divided into three sectors, as shown in FIG. 6.Each sector has, for example, the length of 177 bits, and an 11-bit gapis provided between the sectors. One sector is comprised of a 16-bitpreamble, a 1-bit synchronization, a 24-bit track address and sectoraddress, a 128-bit reproduction control data, and an 8-bit errordetecting code. In this event, the reproduction control data includesthe 2-bit convex/concave identification information [01] indicating thatconvex and concave recording pits are formed in the first recordinglayer RY1 and second recording layer RY2, respectively.

[0051] The controller 25 applies the phase encoding as shown in FIG. 7Aor 7B for each of the preamble, synchronization, track address, sectoraddress, reproduction control data and error correcting code to generatephase encoded signals in accordance with the logical levels of therespective pits. For example, a bit at logical level 0 in thereproduction control data is converted to a phase encoded signal whichrepeats a change between logical levels 1 and 0 in the former halfsection AM of a predetermined duration T, and is fixed at logical level0 in the latter half section PM, as shown in FIG. 7A. On the other hand,a bit at logical level 1 in the reproduction control data is convertedto a phase encoded signal which is fixed at logical level 0 in theformer half section AM of the predetermined duration T, and repeats achange between logical levels 1 and 0 in the latter half section PM, asillustrated in FIG. 7B. The controller 25 repeatedly uses the phaseencoded signals for one sector, generated by the phase encoding, in thethree sectors as illustrated in FIG. 6, to generate phase encodedsignals for one track. The controller 25 further repeatedly supplies theelectron beam irradiating apparatus 10 with the phase encoded signalsfor one track N times. The electron beam irradiating apparatus 10irradiates the surface of the resist layer on the master 15 with anelectron beam only in a period in which the supplied phase encodedsignal is at logical level 1. In this way, the surface of the resistlayer is formed with a data-zero section and a data-one section in thearea corresponding to the PEP area 4 in which pit trains comprised ofthe recording pits Pt2 are recorded in the patterns as illustrated inFIG. 3. The data-zero section and data-one section refer to thosesections on the recording track which are consumed for recording one bitof a variety of data (the preamble, synchronization, track address,sector address, reproduction control data, and error detecting code). Inthis event, the data-zero section refers to a section indicative of adata bit at logical level 0, in which a latent image corresponding tothe recording pit Pt2 is repeatedly formed in the former half sectionAM, while any latent image is not formed in the latter half section PM.On the other hand, the data-one section refers to a section indicativeof a data bit at logical level 1, wherein any latent image is not formedin the former half section AM, while a latent image corresponding to therecording pit Pt2 is repeatedly formed in the latter half section PM. Inthis event, in the PEP area 4, the latent images corresponding to therecording pits Pt2 are formed in alignment to the disc radial direction,i.e., in the direction perpendicular to the recording track, on each ofN recording tracks adjacent to each other. Specifically, in the exampleillustrated in FIG. 3, the phase encoded signals for one trackcorresponding to the reproduction control data are recorded in the PEParea 4 on five recording tracks adjacent to each other in a similarmanner.

[0052] Here, upon completion of recording on the master 15 (formation ofthe latent images on the resist layer), only the latent images formed onthe resist layer of the master 15 are removed to create a resist patternfor forming the first recording layer RY1 (second recording layer RY2).Then, this resist pattern is used to create the first recording layerRY1 which is formed with a pit train comprised of the convex recordingpits Pt1 and Pt2, and the second recording layer RY2 which is formedwith a pit train comprised of the concave recording pits Pt1 and Pt2.

[0053] Next, description will be made on a reproducing apparatus forreproducing recorded information from the recording disc which has thefirst recording layer RY1 and second recording layer RY2, as describedabove.

[0054]FIG. 8 is a diagram illustrating the configuration of thereproducing apparatus.

[0055] In FIG. 8, a pickup 81 irradiates reading beam light to the firstrecording layer RY1 or second recording layer RY2 on a recording disc 80which is rotated by a spindle motor 82. The pickup 81 comprises fourphotodetectors 20 a-20 d arranged in the pattern as illustrated in FIG.1, which individually receive reflected light from the recording disk 80and opto-electrically transduce the reflected light to generate readsignals Ra-Rd, respectively, which are then supplied to a sum readsignal generator circuit 83 and a push-pull read signal generatorcircuit 84, respectively. A slider mechanism 91 moves the pickup 81 inthe disc radial direction.

[0056] The sum read signal generator circuit 83 adds the read signalsRa-Rd to generate a sum read signal R₈, which is supplied to aninformation demodulator circuit 85 and a reproduction control datadecoder circuit 86, respectively. The information data demodulatorcircuit 85 performs predetermined modulation on the sum read signalR_(SUM) to reproduce data recorded in the information data area 1 andlead-in area 2 of the first recording layer RY1 or second recordinglayer RY2, and outputs the reproduced data as reproduction informationdata.

[0057] The reproduction control data decoder circuit 86 applies phasedecoding to a phase encoded signal in the pattern as shown in FIG. 7A or7B, existing in the sum read signal R_(SUM) to recover reproductioncontrol data comprised of data 0 or data 1, which is supplied to thecontroller 10.

[0058] The push-pull read signal generator circuit 83 generates apush-pull read signal R_(pp) through the following processing using theread signal Ra-Rd, and supplies the push-pull read signal R_(pp) to apolarity reversing circuit 88:

R _(pp)=(Ra+Rb)−(Rc+Rd)

[0059] All of the read signals Ra-Rd are not necessarily used forgenerating the push-pull signal R_(pp). In essence, the push-pull readsignal generator circuit 84 is only required to calculate the differencebetween the read signals Ra nd Rd (or Rb and Rc) output from thephotodetectors 20 a and 20 d (or 20 b and 20 c) arranged in thedirection perpendicular to the track, within the photodetectors 20 a-20d, to generate the push-pull read signal R_(pp).

[0060] The polarity reversing circuit 88 reverses the polarity of thepush-pull read signal R_(pp) and supplies a wobble signal processingcircuit 89 and a tracking servo circuit 90, respectively, with thepolarity-reversed push-pull read signal R_(pp) as a push-pull readsignal R_(pp)′ when a polarity reversing signal PV at logical level 1 issupplied from the controller 100. On the other hand, when the polarityreversing signal at logical level 0 is supplied, the polarity reversingcircuit 88 supplies the wobble signal processing circuit 89 and trackingservo circuit 90, respectively, with the push-pull read signal R_(pp) asit is as the push-pull read signal R_(pp)′. The wobble signal processingcircuit 89 extracts disc identification information based on a wobblepattern of a recording pit train formed in the area WE of the lead-inarea 2 illustrated in FIG. 3, based on the push-pull read signalR_(pp)′, and supplies the disc identification information to thecontroller 100.

[0061] The tracking servo circuit 90 closes a tracking servo loop formedof the pickup circuit 81, push-pull read signal generator circuit 84,polarity reversing circuit 88 and tracking servo circuit 90 when atracking servo ON signal is supplied from the controller 100. In thisevent, the tracking servo circuit 90 generates a tracking error signalbased on the push-pull read signal R_(pp)′, and supplies the trackingerror signal to the pickup 81. In response, the pickup 81 biases theoptical axis of the reading beam light in the direction perpendicular tothe track by an amount corresponding to the tracking error signal inorder to make the reading beam light follow the recording pit trainrecorded on the recording disc 80. On the other hand, when a trackingservo OFF signal is supplied from the controller 100, the tracking servocircuit 90 opens the tracking servo loop. This results in a failure inthe operation for making the reading beam light follow the recording pittrain, i.e., the tracking operation.

[0062] Next, description will be made on the operation of thereproducing apparatus illustrated in FIG. 8.

[0063]FIG. 9 is a diagram illustrating a subroutine executed when thereproducing apparatus is loaded with the recording disc 80 for acquiringthe convex/concave identification information.

[0064] First, in FIG. 9, the controller 100 starts rotating the spindlemotor 82 (step S1). Next, the controller 100 supplies a tracking servoOFF signal to the tracking servo circuit 90 (step S2). The execution ofstep S2 causes the tracking servo loop to open. Next, the controller 100controls the slider mechanism 91 in order to move the pickup 81 to thestarting position of the PEP area 4 on the first recording layer RY1(step S3), and controls the pickup 81 to start reading recordedinformation from this position (step S4). The execution of steps S3 andS4 causes the pickup 81 to move to the starting position of the PEP area4 on the first recording layer RY1 and start reading the recordedinformation from this position. In this event, since the tracking servoloop is open, reading beam light irradiated from the pickup 81 traces,for example, on an outlined arrow shown in FIG. 3, such that ittraverses each track in the PEP area 4. As described above, a recordingpit train carrying the reproduction control data, for one turn of thedisc, is formed in the PEP area 4 as it is in a similar manner on aplurality of tracks adjacent to each other. In addition, in the PEP area4, each recording pit Pt2 is recorded such that it is in alignment tothe disc radial direction, i.e., the direction perpendicular to thetrack, as shown in FIG. 3. Therefore, even if the reading beam lightmoves to traverse each track, the pickup 81 can read an equivalent phaseencoded signal from the PEP area 4 to that correctly read from onetrack. Here, the reproduction control data decoder circuit 86 appliesthe phase decoding to the phase encoded signal to recover thereproduction control data comprised of data 0 or data 1 which issupplied to the controller 100.

[0065] The controller 100 extracts the convex/concave identificationinformation from the reproduction control data, stores it in aconvex/concave identification information register 101 (step S5), andreturns to the execution of a main routine (not shown).

[0066] According to the subroutine for acquiring the convex/concaveidentification information illustrated in FIG. 9, the controller 100first reads the convex/concave identification information from the PEParea 4, indicating whether concave or convex recording pits are recordedin each of the first recording layer RY1 and second recording layer RY2of the recording disc 80. Then, the controller 100 stores theconvex/concave identification information in the convex/concaveidentification information register 101.

[0067] Here, for reproducing information data from the information dataarea 1 of the first recording layer RY1 or second recording layer 2 ofthe recording disc 80, the controller 100 executes a subroutine forsetting the polarity of a push-pull read signal, as illustrated in FIG.10.

[0068] In FIG. 10, the controller 100 first determines based on theconvex/concave identification information stored in the convex/concaveidentification information register 101 whether or not concave recordingpits are recorded on a recording layer (first recording layer RY1 orsecond recording layer RY2), from which information is to be reproduced(step S11). Upon determining concave recording pits at step S11, thecontroller 100 supplies a polarity reversing signal PV at logical level1 to the polarity reversing circuit 88 (step S12). With the execution ofstep S12, the polarity reversing circuit 88 reverses the polarity of thepush-pull read signal R_(pp) to generate a push-pull read signal R_(pp)′which is supplied to the wobble signal processing circuit 89 andtracking servo circuit 90, respectively. On the other hand, in failureof determining the concave recording pits at step S11, the controller100 supplies the polarity reversing signal PV at logical level 0 to thepolarity reversing circuit 88 (step S13). With the execution of stepS13, the polarity reversing circuit 88 supplies the push-pull readsignal R_(pp) as it is to the wobble signal processing circuit 89 andtracking servo circuit 90, respectively, as the push-pull signalR_(pp)′. After the execution of step S12 or S13, the controller 100supplies a tracking servo On signal to the tracking servo circuit 90(step S14). Next, the controller 100 controls the pickup 81 in order tostart reading information from the lead-in area 2 of the recording layerfrom which information data is to be reproduced (step S15). With theexecution of steps S14 and S15, the lead-in data is acquired from thelead-in area 2 of the recording layer, from which information data is tobe reproduced, thereby enabling the reproduction of the information datafrom the information data area 1 of the recording layer.

[0069] As described above, in the subroutine for setting the polarity ofthe push-pull read signal as illustrated in FIG. 10, the controller 100first determines based on the convex/concave identification informationread from the PEP area 4 of the recording disc 80 whether or not concaverecording pits are recorded in the recording layer from whichinformation data is to be reproduced. In this event, when determiningthat the recording pits are not concave but convex, the controller 100makes a setting to maintain the polarity of the push-pull read signal,as it is, generated by the push-pull read signal generator circuit 84.On the other hand, when determining the concave recording pits, thecontroller 100 makes a setting to reverse the polarity of the push-pullread signal. Therefore, the tracking control is conducted in accordancewith the push-pull read signal generated by the push-pull read signalgenerator circuit 84 when convex recording pits are recorded in therecording layer from which information data is to be reproduced, whilethe control tracking is conducted in accordance with thepolarity-reversed push-pull read signal when the concave recording pitsare recorded.

[0070] While the foregoing embodiment has been described in connectionwith an exemplary recording disc 90 which has two recording layers (RY1,RY2) as illustrated in FIG. 8, the present invention can be applied in asimilar manner to a recording disc which has a plurality of recordinglayers equal to or more than three. Also, for manufacturing therecording disc, when a disc manufacturer is entrusted to employ theconvex recording pits or concave recording pits, the present inventioncan be applied as well to a single-layer recording disc which has onlyone recording layer, with similar advantages provided therefrom.

[0071] Also, while the foregoing embodiment has been described inconnection with an exemplary recording disc on which convex or concaverecording pits are recorded, the present invention can be applied aswell to a recording disc such as DVD-R which enables information data tobe written thereon by changing a characteristic on a recording surfacethrough phase change recording, magneto-optical recording or the like.

[0072]FIG. 11 is a plan view generally showing how areas are defined onsuch a writable recording disc which is commercially available forgeneral purposes.

[0073] As shown in FIG. 11, the recording disc is divided into aninformation data area 110, a lead-in area 120, a lead-out area 130, anda BCA (burst cutting area) 140.

[0074] The information data area 110 is an area for recording a varietyof information data such as video, audio and computer data. The lead-inarea 120 in turn is an area for recording lead-in data which includesthe recorded position, time required for reproduction, discidentification information and the like for each of information piecesrecorded in the information data area 110. The BCA 140 in turn is anarea in which reproduction control data including tracking information,convex/concave identification information and the like is recorded inthe form of bar codes (later described). The tracking information refersto such information for specifying a tracking method which should beperformed for reading recorded information from the information dataarea 110 and lead-in area 120. The convex/concave identificationinformation in turn refers to such information for specifying whetherthe information data and lead-in data are recorded in a convex portionor a concave portion in the information data area 110 and lead-in area120, respectively.

[0075]FIG. 12 is a diagram, viewed from the top surface of the disc,illustrating patterns in the information data area 110, lead-in area 120and BCA 140, respectively.

[0076] As illustrated in FIG. 12, the information data area 110 andlead-in area 120 are alternately formed with wobbled groove track GT andland track LT in a spiral fashion. As illustrated in FIGS. 13A and 13B,the groove track GT is convex, while the land track LT is concave. Here,for writing information data into the recording disc, a disc recorderintermittently irradiates one of the land track LT and groove track TGwith a recording beam in accordance with the information data. In thisevent, a region irradiated with the recording beam has a characteristic(for example, the reflectivity, magnetization direction and the like)different from that of a region not irradiated with the recording beam.While this region is flat without convex or concave shape like theaforementioned recording pit, this region is hereinafter referred to asthe “virtual pit” because it corresponds to the recording pit. Here,when the recording beam corresponding to information data is irradiatedonto the groove track GT, virtual pits VP are formed on the concavegroove track GT, as illustrated in FIG. 13A. On the other hand, when therecording beam corresponding to information data is irradiated onto theland track LT, virtual pits VP are formed on the convex land track LT,as illustrated in FIG. 13B. In this event, the BCA 140 as shown in FIG.12 includes the convex/concave identification information recorded forspecifying whether the virtual pits VP carrying the information data arerecorded on the concave groove track GT or on the convex land track LT.In the BCA 140, the convex/concave identification information isrepresented by an array pattern of strip-shaped bar pits BP which extendfrom the inner periphery to the outer periphery of the disc as shown inFIG. 12. Therefore, even if the reading beam light traces an outlinedarrow as shown in FIG. 12 because of the tracking servo loop remainingopen, the convex/concave identification information can be read based onthe array pattern of the bar pits BP in a manner similar to the PEP area4.

[0077]FIG. 14 is a plan view generally showing how areas are defined ona recording disc for authoring which is sold only to contracted dealers.

[0078] As shown in FIG. 14, the recording disc is divided into aninformation data area 111, a lead-in area 121, a lead-out area 131, andPEP (phase encoded part) area 141.

[0079] The information data area 111 is an area for recording a varietyof information data such as video, audio and computer data. The lead-inarea 121 in turn is an area for recording lead-in data including arecorded position, time required for reproduction, disc identificationinformation and the like for each of information data pieces recorded inthe information data area 111. The PEP area 141 in turn is an area inwhich reproduction control data, phase encoded as described above, isrecorded, including tracking information, convex/concave identificationinformation and the like. The convex/concave identification informationrefers to such information for specifying whether the information dataand lead-in data should be recorded in a convex portion or a concaveportion of the information data area 111 and lead-in area 121,respectively.

[0080]FIG. 15 is a diagram, viewed from the top surface of the disc,illustrating patterns in the information data area 111, lead-in area 121and PEP area 141, respectively.

[0081] As illustrated in FIG. 15, the information data area 111 andlead-in area 121 are alternately formed with wobbled groove track GT andland track LT in a spiral fashion. As illustrated in FIGS. 13A and 13B,the groove track GT is convex, while the land track LT is concave. Here,when the recording beam corresponding to information data is irradiatedonto the groove track GT, virtual pits VP are formed on the concavegroove track GT, as illustrated in FIG. 13A. On the other hand, when therecording beam corresponding to information data is irradiated onto theland track LT, virtual pits VP are formed on the convex land track LT,as illustrated in FIG. 13B. In this event, the PEP area 141 as shown inFIG. 15 includes the convex/concave identification information which isrecorded for specifying whether the virtual pits VP carrying theinformation data is recorded on the concave groove track GT or on theconvex land track LT. A recording pattern in the PEP area 141 isbasically the same as that illustrated in FIG. 3, except that therecording pits PT are recorded on the wobbled groove track GT or landtrack LT.

[0082] As described above, the recording disc according to the presentinvention has the convex/concave identification information recorded inthe PEP area or BCA area for indicating whether recording pits carryinginformation data is concave or convex, or whether virtual pits arerecorded in a convex portion (land track LT) or a concave portion(groove track GT). In other words, identification information isrecorded in a control data area (PEP area or BCA), from whichinformation can be read when the tracking servo is open, for indicatinga recording pattern of recording marks such as the recording pits orvirtual pits recorded on the recording disc.

[0083] Therefore, the recorded information reproducing apparatusillustrated in FIG. 8 reads the identification information from therecording disc with the open tracking servo, and once stores theidentification information in the convex/concave identificationinformation register 101. Then, the controller 100 supplies the polarityreversing circuit 88 with a polarity reversing signal PV in accordancewith the recording pattern of the recording marks indicated by thisidentification information to set the polarity of the push-pull readsignal.

[0084] According to the present invention, since the polarity of thepush-pull read signal is set in accordance with the recording pattern ofthe recording marks recorded on the recording disc, an informationreproducing operation can be immediately started without trial readingeven in a recorded information reproducing apparatus which employs apush-pull based tracking control.

[0085] This application is based on Japanese Patent Applications Nos.2002-128219 and 2002-258656 which are hereby incorporated by reference.

What is claimed is:
 1. A recording disc for recording information datathereon, comprising: an information data area for recording recordingmarks carrying said information data in columns; and a control data areafor recording identification information indicative of a recordingpattern of said recording marks in said information data area.
 2. Arecording disc according to claim 1, wherein said recording marks arerecording pits, and said identification information is informationindicating whether or not said recording pits are concave or convex. 3.A recording disc according to claim 1, wherein said recording marks areflat virtual pits, and said identification information is informationindicating whether said virtual pits are recorded in a concave portionor a convex portion of said information data area.
 4. A recording discaccording to claim 1, wherein said control data area includes trains ofsaid recording marks carrying said identification informationcorresponding to one track, repeatedly recorded on a plurality of tracksadjacent to each other, and each said recording mark recorded on eachsaid track is in alignment to a direction perpendicular to said tracks.5. A recorded information reproducing apparatus for reproducing recordedinformation from a recording disc having an information data area forrecording recording marks carrying said information data in columns, anda control data area for recording identification information indicativeof a recording pattern of said recording marks in said information dataarea, said apparatus comprising: a reading component for receivingreflected light from said recording disc irradiated with reading beamlight and opto-electrically transducing the reflected light into readsignals by at least two photodetectors arranged in a directionperpendicular to a track; a push-pull read signal generator forcalculating a difference between said read signals generated by saidrespective photodetectors to output the difference as a push-pull readsignal; a tracking servo for biasing the optical-axis of said readinglight beam in the direction perpendicular to the track based on saidpush-pull read signal; an identification information reading componentfor reading said identification information from said control data area;an identifying component for identifying a recording pattern of saidrecording marks recorded in said information data area based on saididentification information; and a polarity reversing component forreversing the polarity of said push-pull read signal in accordance withthe result of the identification made by said identifying component. 6.A recorded information reproducing apparatus according to claim 5,wherein said identification information reading compoent includes: acomponent for opening said tracking servo and forcing said readingcomponent to read information from said control data area; a sum readsignal generating component for adding said read signals output fromsaid reading component to generate a sum read signal; and anidentification information extractor for extracting said identificationinformation from said sum read signal.
 7. A recorded informationreproducing method for reproducing recorded information from a recordingdisc having an information data area for recording recording markscarrying said information data in columns, and a control data area forrecording identification information indicative of a recording patternof said recording marks in said information data area, said methodcomprising: a reading step for receiving reflected light from saidrecording disc irradiated with reading beam light and optoelectricallytransducing the reflected light into read signals by at least twophotodetectors arranged in a direction perpendicular to a track; apush-pull read signal generating step for calculating a differencebetween said read signals generated by said respective photodetectors tooutput the difference as a push-pull read signal; a tracking controlstep for biasing the optical axis of said reading light beam in thedirection perpendicular to the track based on said push-pull readsignal; an identification information reading step for reading saididentification information from said control data area; an identifyingstep for identifying a recording pattern of said recording marksrecorded in said information data area based on said identificationinformation; and a polarity reversing step for reversing the polarity ofsaid push-pull read signal in accordance with the result of theidentification made by said identifying step.
 8. A recording disccomprising a plurality of recording layers, wherein each said recordinglayer includes: an information data area for recording recording pitscarrying information data in columns; and a control data area forrecording a convex/concave identification information indicating withrespect to at least one of said recording layers whether each saidrecording pit recorded on each said recording layer is convex orconcave.
 9. A recording disc according to claim 8, wherein said controldata area includes trains of recording pits carrying said convex/concaveidentification information corresponding to one track, repeatedlyrecorded on a plurality of tracks adjacent to each other, and each saidrecording mark recorded on each said tracks is in alignment to adirection perpendicular to said tracks.
 10. A recorded informationreproducing apparatus for reproducing recorded information from arecording disc having a plurality of recording layers, each saidrecording layer including an information data area for recordingrecording pits carrying information data in columns, and a control dataarea for recording a convex/concave identification informationindicating with respect to at least one of said recording layers whethereach said recording pit recorded on each said recording layer is convexor concave, said apparatus comprising: a reading component for receivingreflected light from said recording disc irradiated with reading beamlight and opto-electrically transducing the reflected light into readsignals by at least two photodetectors arranged in a directionperpendicular to a track; a push-pull read signal generator forcalculating a difference between said read signals generated by saidrespective photodetectors to output the difference as a push-pull readsignal; a tracking servo for biasing the optical axis of said readinglight beam in the direction perpendicular to the track based on saidpush-pull read signal; a convex/concave identification informationreading component for reading said convex/concave identificationinformation from said control data area; a convex/concave identifyingcomponent for identifying the shape of said recording pits recorded inone of said recording layers from which information is to be reproduced,based on said convex/concave identification information; and a polarityreversing component for reversing the polarity of said push-pull readsignal in accordance with the result of the identification made by saidconvex/concave identifying component.
 11. A recorded informationreproducing apparatus according to claim 10, wherein said control dataarea includes trains of said recording pits carrying said identificationinformation corresponding to one track, repeatedly recorded on aplurality of tracks adjacent to each other, and each said recording pitrecorded on each said track is in alignment to the directionperpendicular to said tracks.
 12. A recorded information reproducingapparatus according to claim 10, wherein said convex/concaveidentification information reading component includes: a component foropening said tracking servo and forcing said reading component to readinformation from said control data area; a sum read signal generator foradding said read signals output from said reading component to generatea sum read signal; and a convex/concave identification informationextractor for extracting said convex/concave identification informationfrom said sum read signal.
 13. A recorded information reproducing methodfor reproducing recorded information from a recording disc having aplurality of recording layers, each said recording layer including aninformation data area for recording recording pits carrying informationdata in columns, and a control data area for recording a convex/concaveidentification information indicating with respect to at least one ofsaid recording layers whether each said recording pit recorded on eachsaid recording layer is convex or concave, said method comprising: apush-pull read signal generating step for generating a push-pull readsignal based on read signals read from said recording disc; a trackingcontrol step for biasing the optical axis of said reading light beam ina direction perpendicular to a track based on said push-pull readsignal; a convex/concave identification information reading step forreading said convex/concave identification information from saidrecording disc; a convex/concave identifying step for identifying theshape of said recording pits recorded in one of said recording layersfrom which information is to be reproduced, based on said convex/concaveidentification information; and a polarity reversing step for reversingthe polarity of said push-pull read signal in accordance with the resultof the identification made by said convex/concave identifying step.